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HFS3-v3 Water Injection System

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See What Engines/Models This Product Fits

This product can be used with any car or engine, although additional items may need to accompany it.



Aquamist has been pioneering the IDC based water injection system since 2003 with great success. The HFS3-pwm system is designed to complete the Aquamist's PWM-valve delivery system line-up, it allows precise metering of water/methanol injection for the modern high performance engine. The dash gauge, flow sensor and "Plug and Play" features are standard to minimise installation time.

The system retrieves the fuel flow (IDC) and manifold pressure signals (MPS) from the engine management system as the prime source to control the flow of water. This enables perfect balance of water to fuel flow under all engine loads. The system can also be controlled by a third-party ECU with its own custom water/methanol flow map.

A "Fast Acting Valve" (FAV) controls the delivery rate based on the PWM signal from the HFS-3 controller. A constant line pressure (160 psi) is provided by the Aquatec pump working in the "by-pass" mode. A PWM valve system guarantees wide dynamic range.

There is a non-gauge/flow sensor option (HFS-2) for non-critical application where a failsafe is not needed.

A dash switch is provided instead. The user can disable the system and reduce the manifold pressure to wastegate pressure if needed. 


Choosing water/methanol flow for your application:

100% water:  10-15% water/fuel ratio or 0-5-1cc per BHP 

M50/W50: 15-20% MW/fuel ratio or  1-1.5cc per BHP

100% methanol: 20-25% methanol/fuel ratio or 1.5-2cc per BHP  


Selecting the correct jet or jets for the required flow: 

Calculate the "true" pressure by subtract the 160psi pump pressure by the "boost" pressure

Select the jet or jets from "true" pressure from the chart below (compensated).

Always pick the next size up or allow 10-15% more to allow more headroom.   


Notes on Direct Port application:

Divide the final flow amongst the DP jets

Allow one extra jet for IAT cooling, normally twice the size of the DP jet.  (re-calculate DP jet)

Ideally the DP jet should have an external or internal check valve to minimise vacuum induced after-spray. 

Insert an "high pressure inline filter" before the FAV to minmise the risk of clogging. 

Order extra jet adaptors (806-357N) - Std. kit comes with two.

Recommend using the aquamist Hex Manifold. (comes standard with all compression fittings)

Optional PTFE (4mm) is optional but ideal for combating the heat in the engine compartment. Essential for track or rally events

 Keep hose run to the DP jets as short as possible. Not necessarily need to be "equal" length.

Does not include tank


Please select gauge colour below

Approximate Fitting Time
8.00 hours at £65 per hour = £520 + VAT
£495.90 exc VAT
£595.08 inc VAT